On September 1, 1939, Germany launched its invasion of Poland. Apparently having long anticipated the outbreak of hostilities, Joseph Hollander and his wife Felicia (Lusia) had already departed Cracow and were residing in the town of Zaleszczyki in the southeastern corner of Poland on the Romanian border. On September 6, Joseph procured a visa from the Romanian consulate in Lvov to enter Romania and, still far from the advancing German army, returned to Zaleszczyki to await further events. On September 17, in accordance with the Nazi–Soviet Non-Aggression Pact, the Red Army entered Poland from the east to secure those territories of Poland promised by Hitler to Stalin as the price of the latter's neutrality. The zone soon to be occupied by the Red Army included the region of Eastern Galicia and the border town of Zaleszczyki. On the following day, September 18, Joseph and Lusia promptly crossed into Romania, leaving Poland forever.

The rest of Joseph's family – his mother, his three sisters and their husbands, and two nieces – had remained in Cracow until the outbreak of the war. The German army reached their city on September 6. Like so many others, they apparently attempted a panicked escape (in contrast to the well-laid plans of Joseph) ahead of the rapidly advancing German army but were almost immediately overtaken by events and had to return to the city. Several of their subsequent letters referred obliquely to this failed escape attempt.